The error implies the XML you are trying to XOG in is badly formatted. Honestly I moved over to the Xog Bridge tool (search the boards for some posts, or just google), its so much easier than dealing with the official XOG client that I haven't looked back. I'd recommend giving that a shot, as I'm sure would many others around here.

Hi Elias, Thanks for the reply. I'm using the XOG Bridge to run the XOGs. Why do you understand it is badly formatted? I'm using this GEL Script and running successfully on a process. The problem only happens when I run the bpm_process writing XOG.

The error given is "The prefix "xog" for element "xog:Login" is not bound" which implies a malformed XML, but I also think I misunderstood the issue. Are you trying to XOG out and in a process that contains the posted GEL script, or are you using the GEL script to create an XML document that you then are XOGging in to another environment? Can you post the XML you are trying to XOG?